Dispersant compositions containing a diisobutyl ester of a dicarboxylic acid and a polyurethane-based dispersant

ABSTRACT

Dispersant compositions are described which contain: (a) a carrier medium comprising a ternary mixture of diisobutyl esters of succinic acid, glutaric acid and adipic acid, the carrier medium present in an amount of from 10 to 80% by weight based on the composition; and (b) one or more polyurethane dispersants present in an amount of from 20 to 90% by weight based on the composition.

FIELD OF THE INVENTION

This invention relates to dispersant compositions for paintformulations, these dispersant compositions being liquid and pourable at25° C. and being based on a special carrier medium and apolyurethane-based dispersant.

Prior Art

Dispersants are used in paint manufacture largely for the followingreasons:

-   a) to disperse the film former,-   b) to disperse pigments and fillers and-   c) to disperse other additives which may be present in paint    formulations, for example hardening accelerators, thickeners, flow    controllers, flatting agents, preservatives.

As the expert is aware, paint manufacturers generally seek to have thecomponents used for the production of paint formulations available in aform which allows for easy handling. A major advantage in this regard isif a component is present in liquid rather than solid form and can bepoured at room temperature (room temperature in the context of thepresent invention is understood to be a temperature of 25° C. This isroutinely achieved by the use of solvents. In principle, suitablesolvents are on the one hand water and, on the other hand, organicsolvents. However, there are instances where, on the one hand, water isnot suitable because it is unable satisfactorily to dissolve thedispersant or because the dispersant is not permanently stable in waterand where, on the other hand, organic solvents are not suitable. Thelatter point is of increasing importance because organic solvents havebecome increasingly unattractive for environmental reasons so thatsubstantial freedom from VOCs (volatile organic compounds) is desirable.Accordingly, there is a constant demand for dispersants to be presentedin a form which is not attended by any of the above-mentioneddisadvantages.

DESCRIPTION OF THE INVENTION

The problem addressed by the present invention was to provide dispersantcompositions which would consist of a carrier medium and one or moredispersants and which would satisfy the following conditions: thecompositions would be liquid at 25° C., homogeneous, concentrated,pourable, stable in storage and substantially free from VOCs.

By “homogeneous” is meant that the dispersant is homogeneously dispersedin the carrier medium. By “concentrated” is meant that the compositioncontains at least 20% by weight of the dispersant, based on thecomposition as a whole. “Pourable” means that the Brookfield viscosityof the composition, as measured at 25° C./25 r.p.m., is below 50,000mPas. “Stable in storage” is understood to mean that, even in the eventof prolonged storage, the composition remains stable both chemically (nodecomposition of the components) and in regard to consistency (no lossof homogeneity). “Substantially free from VOCs” is understood to meanthat the composition contains hardly any volatile substances. This meansin particular that the carrier medium of the composition is of lowvolatility.

In addition, the composition of the carrier medium should be such thatno adverse interactions occur when the combination of carrier medium anddispersant is used for the production of a paint formulation where itinevitably comes into contact with film formers, pigments, fillersand/or paint additives.

The present invention relates to dispersant compositions for paintformulations which are liquid and pourable at 25° C. and which consistof

-   a) 10 to 80% by weight of a carrier medium in the form of one or    more diisobutyl esters of C₄₋₆ dicarboxylic acids and-   b) 20 to 90% by weight of one or more polyurethane dispersants for    paint formulations.

It has surprisingly been found that the compositions according to theinvention solve the problem stated above excellently in every respect.The compositions are liquid, homogeneous, pourable and stable instorage. They are also distinguished by substantial freedom from VOCs.

The VOC content of a composition can be determined by methods known tothe relevant expert. In the context of the present invention,substantial freedom from VOCs is understood to mean a VOC value of lessthan 0.5% and preferably less than 0.2%, based on the composition as awhole. In the context of the present invention, the VOC content of asample is determined in accordance with DIN 75201 (“Determination of theFogging Behavior of Materials Used for the Interior Trim of MotorVehicles”) using the following procedure: the sample is placed on thebottom of a lip-free glass beaker with fixed dimensions. The beaker iscovered with an aluminium foil on which volatile constituents from thetest specimen or the sample are able to condense. The aluminium foil iscooled. The beaker thus prepared is placed for 16 hours in a baththermostat set to a test temperature of 100±0.3° C. The effect of thefogging deposit on the aluminium foil is quantitatively determined byweighing the foil before and after the fogging test. The VOC value iscalculated in accordance with the following equation:VOC value (%)=(A/B)*100where

-   A is the weight of the fogging deposit (in g) and-   B is the weight of the sample used (in g).

In addition, the compositions according to the invention are compatiblewith film formers, pigments, fillers and paint additives which arenormally used in the production of paint formulations.

The carrier medium a) consists of one or more diisobutyl esters of C₄₋₆dicarboxylic acids. The diisobutyl esters to be used may therefore beused individually or in admixture with one another.

Preferred dicarboxylic acids are succinic acid, glutaric acid and adipicacid.

Binary dicarboxylic acid mixtures suitable for use as component a) aresuccinic acid/glutaric acid, succinic acid/adipic acid and glutaricacid/adipic acid.

Particular preference is attributed to ternary mixtures of succinicacid, glutaric acid and adipic acid, particularly those use by theexpert in the production of Nylon, for example ternary mixturesconsisting of ca. 25% by weight succinic acid, 50% by weight glutaricacid and 25% by weight adipic acid.

The dispersant b) is a polyurethane. Any polyurethanes known to therelevant expert may be used. One embodiment is characterized by the useof polyurethanes known to the relevant expert which contain thefollowing structural elements:

-   -   oligomeric caprolactone blocks started with linear C₆₋₁₈        alcohols or with amines containing additional tert.amine groups        or alcohols,    -   amines substituted by tert.amine groups or alcohols,    -   oligomeric dihydroxy-terminated ethylene oxide blocks (as        described in EP 154 678, for example, as particularly effective        dispersants for organic paint systems).

The structural elements mentioned are reacted individually or incombination with polyfunctional, preferably tetrafunctional,polyisocyanates for the production of the polyurethanes.

In a preferred embodiment, the compounds to be used as component b) havea solubility of at least 20% by weight in a mixture consisting of 25% byweight of succinic acid diisobutyl ester, 50% by weight of glutaric aciddiisobutyl ester and 25% by weight of adipic acid diisobutyl ester.

In addition, the dispersants b) suitable for the purposes of theinvention may be used individually or in admixture with one another.

Suitable polyurethanes are, in particular, the nonvolatile polymericactive components of standard commercial products such as, for example,Disperbyk 163 (Byk Chemie) or Texaphor P60 and Texaphor P63 (CognisDeutschland GmbH) which, in supply form, have hitherto been marketedexclusively in volatile organic solvents, such as xylene, butyl acetateor methoxypropyl acetate, and used in this form by the user.

The dispersants b) suitable for the purposes of the invention may beused individually or in admixture with one another.

The present invention also relates to the use of the above-describeddispersant compositions in the production of paint formulations.

EXAMPLES Substances Used

-   Texaphor P 60: block copolymer of oligocaprolactone, oligoethylene    oxide and adhering terminal groups bearing t-amino groups (50%    polymer solution in butyl acetate/xylene, a product of Cognis    Deutschland GmbH)-   Texaphor P 63: block copolymer of oligocaprolactones, long-chain    alkyl groups and adhering terminal groups bearing t-amino groups    (45% polymer solution in methoxypropyl acetate/butyl acetate, a    product of Cognis Deutschland GmbH)-   KE 1000: diisobutyl ester of a mixture of linear C₄₋₆ dicarboxylic    acids (Cognis Deutschland GmbH)

Dispersant Compositions Example 1

250.0 g Texaphor P 60 and 125.0 g KE 1000 were introduced into a 1-literglass flask and heated to 100° C. in vacuo (150 mbar) in a rotaryevaporator. After most of the solvent had been removed, a gentle streamof nitrogen was passed over the surface of the reaction mixture—whilethe vacuum of ca. 150 mbar was maintained—until weight was constant.Yield of product: 250.0 g. Characterization of the product: clear, lightyellow composition of honey-like consistency, Brookfield viscosity (asmeasured at 20 r.p.m., 25° C., spindle 6): 42.4 Pas.

Example 2

1111.1 g Texaphor P 63 and 500.1 g KE 1000 were introduced into a1-liter glass flask and heated to 100° C. in vacuo (150 mbar) in arotary evaporator. After most of the solvent had been removed, a gentlestream of nitrogen was passed over the surface of the reactionmixture—while the vacuum of ca. 150 mbar was maintained—until weight wasconstant. Yield of product: 1000.0 g. Characterization of the product:clear, light yellow composition of honey-like consistency, Brookfieldviscosity (as measured at 20 r.p.m., 25° C., spindle 6): 7.0 Pas.

1-2. (Canceled)
 3. A dispersant composition comprising: (a) a carriermedium comprising a ternary mixture of diisobutyl esters of succinicacid, glutaric acid and adipic acid, the carrier medium present in anamount of from 10 to 80% by weight based on the composition; and (b) oneor more polyurethane dispersants present in an amount of from 20 to 90%by weight based on the composition.
 4. The dispersant compositionaccording to claim 3, wherein the one or more polyurethane dispersantscomprises a polyurethane having a solubility at least 20% by weight in amixture comprising 25% by weight of succinic acid diisobutyl ester, 50%by weight of glutaric acid diisobutyl ester and 25% by weight of adipicacid diisobutyl ester.
 5. The dispersant composition according to claim3, wherein the composition is substantially free from VOC's.
 6. Thedispersant composition according to claim 4, wherein the composition issubstantially free from VOC's.
 7. The dispersant composition accordingto claim 3, wherein the composition is liquid and pourable at 25° C. 8.The dispersant composition according to claim 4, wherein the compositionis liquid and pourable at 25° C.
 9. The dispersant composition accordingto claim 5, wherein the composition is liquid and pourable at 25° C. 10.The dispersant composition according to claim 6, wherein the compositionis liquid and pourable at 25° C.
 11. A dispersant compositioncomprising: (a) a carrier medium comprising a ternary mixture ofdiisobutyl esters of succinic acid, glutaric acid and adipic acid, thecarrier medium present in an amount of from 10 to 80% by weight based onthe composition; and (b) one or more polyurethane dispersants present inan amount of from 20 to 90% by weight based on the composition, whereinthe one or more polyurethane dispersants comprises a polyurethane havinga solubility at least 20% by weight in a mixture comprising 25% byweight of succinic acid diisobutyl ester, 50% by weight of glutaric aciddiisobutyl ester and 25% by weight of adipic acid diisobutyl ester;wherein the composition is liquid and pourable at 25° C., and whereinthe composition is substantially free from VOC's.
 12. A paintformulation comprising a dispersant composition according to claim 3.13. A paint formulation comprising a dispersant composition according toclaim 11.